A hydrogel is a biphasic material, a mixture of porous, permeable solids and at least 10% by weight or volume of interstitial fluid composed completely or mainly by water.[1][2] In hydrogels the porous permeable solid is a water insoluble three dimensional network of natural or synthetic polymers and a fluid, having absorbed a large amount of water or biological fluids.[2][3][4][5] These properties underpin several applications, especially in the biomedical area. Many hydrogels are synthetic, but some are derived from nature.[6][7] The term 'hydrogel' was coined in 1894.[8]
^Cite error: The named reference :2 was invoked but never defined (see the help page).
^Bemmelen JM (1907). "Der Hydrogel und das kristallinische Hydrat des Kupferoxydes". Zeitschrift für Chemie und Industrie der Kolloide. 1 (7): 213–214. doi:10.1007/BF01830147. S2CID197928622.